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Re: Well formed verses Valid code


From: Alastair Campbell
Date: Feb 27, 2007 2:40AM

Andrew Kirkpatrick wrote:
> My responses are largely in response to Alastair's "I'm convinced that
> well-formed (X)HTML should be an accessibility (as well as good
> practice) requirement" statement. I'm not convinced that it should be
> an accessibility requirement, but I am convinced that a robust
> development process will address validity issues for other reasons.

I'm sorry I don't have an example of an issue to hand, but isn't it a
logical extension of the reasoning for valid code? I'm preaching to the
choir here, but guess I need to, to work out where our reasoning

We use valid code to be sure that various user agents render the content
as expected. (Of course they don't in practice, but at least then we
know it's a bug of that user agent and therefore their responsibility.)

Visual rendering issues in common browsers will be caught because people
generally include a cross-browser checks as part of the development

Those cross-browser checks are with a limited set of browsers (e.g.
http://developer.yahoo.com/yui/articles/gbs/index.html). Therefore a
normal development process does not include all browsers, let alone all
assistive technologies.

Since each of these assistive technologies could render non-valid code
differently, the best thing you can do within a reasonable effort is
ensure that you use valid code, and check common user agents.

It may be that an ampersand in an href is not going to affect any known
user agent, but if you're going to provide a guide for developers, I'd
keep it simple: use valid code. I have been in situations where
developers were reluctant to use valid code because it meant changing
their CMS, so I don't think it will necessarily be caught by other parts
of the process.

If HTML5 uses a schema rather than DTD based method for checking, that's
fine to (and I believe goes some way to addressing your concern), but in
the mean time, I'll keep pointing people to the W3C validator.

Kind regards,


Alastair Campbell | Director of User Experience

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